Portion of an electronic mouse



FIG. 1 is a front perspective view of a portion of an electronic mouse showing my new design;

FIG. 2 is a rear perspective view thereof; and,

FIG. 3 is a left side view thereof.

The broken line showing of the remainder of the electronic mouse is for illustrative purposes and forms no part of the claimed design. The unshown bottom of the electronic mouse forms no part of the claimed design. 

The ornamental design for a portion of an electronic mouse, as shown and described. 